Shim layer abstraction in multi-protocol SDN controller

ABSTRACT

A Service Abstraction Layer (SAL) provides network level abstraction enabling applications to interface via multiple software-defined networking (SDN) protocols with network devices in a heterogeneous network (devices in the network support a variety of SDN protocols) and in an opaque fashion in order to fulfill desired services by one or more of the protocols. Abstraction is not limited or mapped to any particular protocol. Protocols can change and applications can vary. Support for new protocols can be added later as plug-ins.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/968,411, filed Mar. 21, 2014, the entirety of which isincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to software-defined networking (SDN).

BACKGROUND

An SDN controller is used to communicate with network devices in anetwork to control various functions of the network devices. SDNcontrollers tend to support a single particular protocol, such as theOpenFlow protocol, and thus are limited only to greenfield environments.In reality, there are deployments in which there are devices withdifferent capabilities and which are configured to use different SDNprotocols.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a system block diagram showing a SDN controller in a network,according to an example embodiment.

FIG. 2 is an architectural diagram of the SDN controller, applicationsand network devices, according to an example embodiment.

FIG. 3 is a diagram depicting a Service Abstraction Layer of the SDNcontroller, according to an example embodiment.

FIG. 4 is a software architectural diagram of the various functionallayers of the system depicted in FIG. 2, according to an exampleembodiment.

FIG. 5 is a flow chart of a method according to an example embodiment.

FIG. 6 is a block diagram of the SDN controller, according to an exampleembodiment.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

In accordance with one embodiment, a software defined network (SDN)controller receives one or more requests for services to be performed bya plurality of network devices that communicate with the SDN controllerby a plurality of different of SDN protocols. The requests are mapped toappropriate ones of the plurality of different SDN protocols to fulfilthe services of the requests. The SDN controller sends to respectiveones of the plurality of network devices control messages according toappropriate ones of the plurality of different SDN protocols.

Example Embodiments

Referring first to FIG. 1, a diagram is shown of a system 10 thatincludes a plurality of network devices 20(1)-20(N), a Software-DefinedNetworking (SDN) controller 30 and a plurality of applications40(1)-40(K). The network devices 20(1)-20(N) may be configured tocommunicate with the SDN controller 30 using a different one of aplurality of SDN control protocols that are depicted by the arrowslabeled 25(1)-25(N) in FIG. 1. Consequently, the SDN controller 30 is amulti-protocol SDN controller in that it can communicate with networkdevices which use different SDN protocols. There need not be aone-to-one correspondence between SDN protocol and network device. Thatis, some network devices may be capable of communicating using more thanone SDN protocol.

Turning now to FIG. 2, with continued reference to FIG. 1, themulti-protocol SDN controller 30 can support multiple SDN protocolsbetween it and the network devices 20(1)-20(N) it controls. In theexample shown in FIG. 2, the network devices 20(1)-20(N) include networkdevices from a first vendor (called Vendor 1) shown at reference numeral22 and network devices from one or more other vendors, called Non-Vendor1 network devices shown at reference numeral 24.

There are northbound application programming interfaces (APIs) 32 thatenable communication between the applications 40(1)-40(k) and the SDNcontroller 30. The northbound APIs 32 are expandable on demand. Examplesof northbound APIs 32 include an API compliant with the Open ServiceGateway Initiative (OSGI) 32(1) and a Representational state transfer(RESTful) API 32(2).

Similarly, there are southbound APIs 34 that enable communicationbetween the SDN controller 30 and the network devices 20(1)-20(N). Thesouthbound APIs 34 include dynamic plugins for different SDNcommunication protocols. Examples of southbound APIs include an API34(1) compliant with the Cisco One Platform Kit (OnePK), an API 34(2)compliant with the Path Computation Element Communication Protocol(PCEP), an API 34(3) compliant with the Interface to Routing System(I2RS) standard, an API 34(4) compliant with the OpenFlow OF1.xstandard, and a Command Line Interface (CLI) 34(4).

The SDN controller 30 includes several functional subsystems, includingan infrastructure (core) subsystem 35, a controller applicationssubsystem 36 and a controller components subsystem 37. All of thesesubsystems may be implemented as Java™ bundle, in one example.

Examples of functional blocks in the infrastructure subsystem 35 includea Dijkstra Shortest Path First (SPF) 50, Forwarding Rules Manager 52,Physical and Logical Topology Manager 54, Switch Manager 56, HostTracker 58, Address Resolution Protocol (ARP) Handler 60 and DeviceManager 62. The Physical and Logical Topology Manager 54 imports atopology from inventory or other sources. The Dijkstra SPF 50 andForwarding Rules Manager 52 provide for advanced feature setcapabilities.

Examples of functional blocks in the controller applications subsystem36 include a Flow Manager 70, Slice Manager 72 and Topology IndependentForwarding (TIF) 74. The controller components subsystem 37 includes aGraphical User Interface (GUI) 80, an Authentication block 82 and aTroubleshooting block 84. The components for the controller applicationssubsystem 36 are used for deployment in a production network.

The applications 40(1)-40(K) running above the SDN controller 30 need tobe opaque to the variety of SDN protocols. A Service Abstraction Layer(SAL) 90 is provided that is a shim layer abstraction in theinfrastructure subsystem 35.

Network level abstraction enables applications to interface via multipleSDN protocols with network devices in a heterogeneous network (devicesin the network support a variety of SDN protocols) in an opaque fashionin order to fulfill desired services by one or more of the protocols.Abstraction is not limited or mapped to any particular protocol.Protocols can change and applications can vary. In addition, support fornew protocols can be added as plugins.

Most SDN controllers support only the OpenFlow SDN protocol in thesouthbound direction (to send control messages from the controller tothe network devices) to communicate with the network devices (which inthis case is limited to OpenFlow switches). Consequently, the networkapplications on top of the SDN controller are limited to thecapabilities of the OpenFlow switches (and OpenFlow protocol). Alsogiven that the OpenFlow protocol is relatively new at the time of thiswriting, there are many existing network devices which do not supportOpenFlow or cannot be upgraded to support OpenFlow. There are severalnew protocols that may be developed or are already under development andit is important for SDN controllers to be inclusive and support a widevariety of devices and protocols.

The SAL 90 provides this functionality. The SAL 90 provides a set ofservices which applications 40(1)-40(K) or modules north of the SDNcontroller 30 (running on and above the SDN controller) can use. In thesouthbound direction (from the controller 30 to the network devices20(1)-20(N)), the SAL 90 supports a multitude of protocols tocommunicate with network devices depending on the capabilities of thedevices. The SAL 90 maps the services to the capabilities of the networkdevices and selects the appropriate southbound protocol to fulfill (orrender) the services.

The SAL 90 provides a plugin mechanism whereby southbound protocolsupport is developed and attached to the SAL 90. This makes the SDNcontroller 30 extensible and capable of supporting a network withheterogeneous devices of varying capabilities and capable ofcommunicating using different protocols.

The services exposed by the SAL 90 provide a higher level abstractionthat hides the details of the southbound protocol plugins and how agiven service is fulfilled (or rendered) by a specific device. It thusallows a given service (associated with an application) to be fulfilledacross devices of different capabilities. That is, the SAL 90 provides apath service for a traffic flow to follow in a network made of severaldifferent types of network devices.

This path may use any network technology, such as a virtual local areanetwork (VLAN), General Routing Encapsulation (GRE), Multiprotocol LabelSwitching (MPLS) tunnel or Virtual Extensible Local Area Network (VXLAN)tunnel, etc., depending on the network device capability. To establishthis path, the controller programs the device and the SAL allows thecontroller to use, for example, the OpenFlow protocol with an OpenFlowswitch, Simple Network Management Protocol (SNMP) or CLI to configure anon-OpenFlow switch.

The SAL 90 provides the ability to map a higher level abstraction(exposed as service sets) to a device capability, and to the protocolcapabilities. In so doing, the SAL 90 selects the appropriate protocolprimitives to communicate the service intent to a network device.Examples of protocol APIs that the SAL 90 may abstract to are shown atreference numerals 34(1)-34(5) in FIG. 2 and described above. Thesesouthbound protocol APIs are meant only to be examples, and APIs forother protocols now known or hereinafter developed may be supportedaccording to the techniques presented herein.

Reference is now made to FIGS. 3 and 4. FIG. 3 shows more details of theSAL 90 and FIG. 4 shows how the SAL 90 fits within the overall softwarearchitecture of the system depicted in FIG. 2. Business logic modules(shown generally at 100) interact with the SAL 90 through genericservice requests and responses. Examples of such business logic modules100 include the aforementioned Forwarding Manager 52, Topology Manager54, Switch Manager 56, Host Tracker 58, Slice Manager 72, and aStatistics Manager 102.

The SAL 90 includes a Services Manager 110 and a Plugin Manager 120. TheServices Manager 110 manages generic services, such as network devicediscovery, etc. Services are constructed using individual featuresexposed by the Plugin Manager 120 (based on Plugin availability andnetwork device capabilities). The Services Manager 110 includes aservice-to-feature registry 112. The Plugin Manager includes a database122 that stores device capability-based feature-to-plugin mappinginformation. The Services Manager 110 sends a feature request 114 to thePlugin Manager 120 and the Plugin Manager 120 sends an abstracted pluginresponse 124.

Examples of plugins are shown at 126(1)-126(4), and include an OpenFlow(OF) plugin 126(1), a OnePK plugin 126(2), a vendor-specific OF plugin126(3) and an I2RS plugin 126(4). Each plugin works independently of oneanother and is loosely coupled with the Services Manager 110. The PluginManager 120 selects plugins dynamically based on the feature request ona given network device or set of network devices.

The SAL 90, and specifically the Plugin Manager 120, is the only placewhere plugin details are exposed. Therefore, no cross-contaminationacross plugins and no contamination in business logic layers can occur.

FIG. 4 illustrates a software/functional layer view. In the exampleshown in FIG. 4, SDN protocols 25(1)-25(4) are shown for use intransporting controls to network elements 20(1)-20(N). The SDNcontroller 30 selects the appropriate protocol based on devicecapability negotiation. The SAL 90 selects one of the API libraries34(1)-34(4). At the northbound side of the controller 30, FIG. 4 showsAPIs 32(1) exposed by OSGI services, bidirectional HTTP RESTful APIs32(2) and another bidirectional API 32(3). An application using OSGIreferences is shown at reference numeral 40(1). Such an application mayrun on Java or Python platforms inside a container or remotely, and maycommunicate via the APIs 32(1) using Java native function calls orRemote Procedure Calls (RPC). Similarly, FIG. 4 shows an application40(2) that runs remotely and uses HTTP RESTful APIs. APIs 32(3) may beconfigured to support communication with applications running on theApache Thrift platform.

Reference is now made to FIG. 5. FIG. 5 illustrates a flow chartdepicting operations of a method 200 performed by an SDN controller,according to an example embodiment. At 210, an SDN controller receivesone or more requests for services to be performed by a plurality ofnetwork devices that communicate with the SDN controller by a pluralityof different of SDN protocols. At 220, the SDN controller maps therequests to appropriate ones of the plurality of different SDN protocolsto fulfil the services of the requests. At 230, the SDN controller sendsto respective ones of the plurality of network devices control messagesaccording to appropriate ones of the plurality of different SDNprotocols.

As explained above, the SDN controller stores, for each SDN protocol,one or more libraries of primitives used for communicating with anetwork device in accordance with a corresponding SDN protocol. Thelibraries of primitives provide an abstraction so as to hide details ofthe plurality of different SDN protocols from the plurality ofapplications. Thus, the mapping operation involves selecting primitivesof respective ones of the plurality of SDN protocols to communicate arequest for services of an application to a network device. To do so,the SDN controller stores information that maps network devicecapability based features to plugins to the plurality of different SDNprotocols, and dynamically selects a plugin based on a feature containedin a request to a given network device or set of network devices.Plugins are changed or added to accommodate changes or additions to theSDN protocols.

In summary, the SDN controller includes a services abstraction layerthat provides network level abstraction enabling applications tointerface via multiple SDN protocols with network devices in aheterogeneous network (devices in the network that supports a variety ofSDN protocols) in an opaque fashion in order to fulfill desired servicesby one or more of the protocols. Abstraction is not limited or mapped toany particular protocol. Protocols can change and applications can vary.Support for new protocols can be added later as plugins.

Turning now to FIG. 6, a block diagram is shown of the SDN controller30. The SDN controller 30 includes a network interface unit 310, one ormore processors 320 and memory 330. Within memory 330 are storedsoftware instructions for SDN controller software 340 and also storeddata 350 for SDN protocol libraries. The memory 330 may comprise readonly memory (ROM), random access memory (RAM), magnetic disk storagemedia devices, optical storage media devices, flash memory devices,electrical, optical, or other physical/tangible memory storage devices.The processor 320 is, for example, a microprocessor or microcontrollerthat executes instructions for the SDN controller software 340. Thus, ingeneral, the memory 330 may comprise one or more tangible(non-transitory) computer readable storage media (e.g., a memory device)encoded with software comprising computer executable instructions andwhen the software is executed (by the processor 320) it is operable toperform the operations described herein in connection with the SDNcontroller software 340. The SDN controller software 340 may beimplemented as a Java™ virtual machine, running on a server in a datacenter or other cloud computing environment. The SDN controller software340 includes instructions for performing the functions of the describedabove in connection with FIGS. 1-5.

In summary, a method is provided, comprising: at a software definednetwork (SDN) controller, receiving one or more requests for services tobe performed by a plurality of network devices that communicate with theSDN controller by a plurality of different of SDN protocols; mapping therequests to appropriate ones of the plurality of different SDN protocolsto fulfil the services of the requests; and sending from the SDNcontroller to respective ones of the plurality of network devicescontrol messages according to appropriate ones of the plurality ofdifferent SDN protocols.

Similarly, an apparatus is provided comprising: a network interface unitto send and receive communications over a network; a memory that storeslibraries of primitives used for communicating with a plurality ofnetwork devices in accordance with a plurality of different softwaredefined networking (SDN) protocols; a processor coupled to the networkinterface, that: maps received requests for services to be performed bythe plurality of network devices to appropriate ones of the plurality ofdifferent SDN protocols; and causes control messages to be sent torespective ones of the plurality of network devices according toappropriate ones of the plurality of different SDN protocols.

Further still, one or more computer readable storage media are providedencoded with software comprising computer executable instructions andwhen the software is executed by a processor, cause the processor to:map received requests for services to be performed by a plurality ofnetwork devices to appropriate ones of a plurality of differentsoftware-defined networking (SDN) protocols; and cause control messagesto be sent to respective ones of the plurality of network devicesaccording to appropriate ones of the plurality of different SDNprotocols.

While various embodiments are disclosed herein, it should be understoodthat they have been presented by way of example only, and notlimitation. It will be apparent to persons skilled in the relevant artthat various changes in form and detail may be made therein withoutdeparting from the spirit and scope of what is described herein. Thus,the breadth and scope of the claims should not be limited by any of theexample embodiments disclosed herein.

What is claimed is:
 1. A method comprising: at a software definednetwork (SDN) controller, receiving from a plurality of applications viaapplication programming interfaces (APIs) of different types requestsfor services to be performed by a plurality of network devices thatcommunicate with the SDN controller by a plurality of different SDNprotocols; mapping the requests for services to appropriate ones of theplurality of different SDN protocols to fulfil the services of therequests, wherein the mapping includes, for each request for services:generating a feature request from the request for services based on aservice-to-feature-registry; storing information that maps networkdevice capability based features to a plurality of plugins each for arespective one of the plurality of different SDN protocols; anddynamically selecting one of the plurality of plugins based on a featurecontained in the feature request to a given network device or set ofnetwork devices, wherein the mapping between the requests for servicesand the plugins is performed in a services abstraction layer so as toprovide network level abstraction enabling the plurality of applicationsto interface via the different SDN protocols with the network devices toimplement a heterogeneous network in which the network devices supportthe different SDN protocols in an opaque fashion in order to fulfill therequests for services using the different SDN protocols; and sendingfrom the SDN controller to respective ones of the plurality of networkdevices control messages from the selected plugins according toappropriate ones of the plurality of different SDN protocols.
 2. Themethod of claim 1, further comprising storing, for each SDN protocol,one or more libraries of primitives used for communicating with anetwork device in accordance with a corresponding SDN protocol.
 3. Themethod of claim 2, wherein the libraries of primitives provide anabstraction so as to hide details of the plurality of different SDNprotocols from the plurality of applications.
 4. The method of claim 2,wherein mapping comprises selecting primitives of respective ones of theplurality of SDN protocols to communicate a request for services of anapplication to a network device.
 5. The method of claim 1, furthercomprising constructing services using individual features exposed by aplugin manager on behalf of the plurality of plugins.
 6. The method ofclaim 1, further comprising changing or adding plugins in order toaccommodate changes or additions to the SDN protocols.
 7. The method ofclaim 1, wherein the SDN controller includes: a northbound layer thatincludes the APIs of different types for receiving the requests forservices from the plurality of applications; and a southbound layer thatincludes the plurality of plugins, wherein the service abstraction layeris coupled between the northbound layer and the southbound layer.
 8. Themethod of claim 1, wherein the different SDN protocols include at leastan Open Flow SDN protocol.
 9. An apparatus comprising: a networkinterface unit to send and receive communications over a network; amemory; and a processor coupled to the network interface and the memory,that: receives from a plurality of applications via applicationprogramming interfaces (APIs) of different types requests for servicesto be performed by a plurality of network devices that communicate withthe network interface unit by a plurality of different SDN protocols;maps the requests for services to appropriate ones of the plurality ofdifferent SDN protocols to fulfil the services of the requests, whereinthe processor is configured to map the requests by, for each request forservices: generating a feature request from the request for servicesbased on a service-to-feature-registry; storing information that mapsnetwork device capability based features to a plurality of plugins eachfor a respective one of the plurality of different SDN protocols; anddynamically selecting one of the plurality of plugins based on a featurecontained in the feature request to a given network device or set ofnetwork devices, wherein the processor is configured to perform the mapoperation between the requests for services and the plugins in aservices abstraction layer so as to provide network level abstractionenabling the plurality of applications to interface via the differentSDN protocols with the network devices to implement a heterogeneousnetwork in which the network devices support the different SDN protocolsin an opaque fashion in order to fulfill the requests for services usingthe different SDN protocols; and sends, from the network interface unitto respective ones of the plurality of network devices, control messagesfrom the selected plugins according to appropriate ones of the pluralityof different SDN protocols.
 10. The apparatus of claim 9, wherein thememory stores, for each SDN protocol, one or more libraries ofprimitives used for communicating with a network device in accordancewith a corresponding SDN protocol.
 11. The apparatus of claim 10,wherein the libraries of primitives provide an abstraction so as to hidedetails of the plurality of different SDN protocols from the pluralityof applications.
 12. The apparatus of claim 10, wherein the processorselects primitives of respective ones of the plurality of SDN protocolsto communicate a request for services of an application to a networkdevice.
 13. The apparatus of claim 9, wherein the processor changes oradds plugins in order to accommodate changes or additions to the SDNprotocols.
 14. One or more non-transitory computer readable storagemedia encoded with software comprising computer executable instructionsand when the software is executed by a processor, cause the processorto: receive from a plurality of applications via application programminginterfaces (APIs) of different types requests for services to beperformed by a plurality of network devices that communicate by aplurality of different SDN protocols; map the requests for services toappropriate ones of the plurality of different SDN protocols to fulfilthe services of the requests, wherein the instructions to cause theprocessor to map include instructions to cause the processor to, foreach request for services: generate a feature request from the requestfor services based on a service-to-feature-registry in a servicemanager; store information that maps network device capability basedfeatures to a plurality of plugins each for a respective one of theplurality of different SDN protocols; and dynamically select one of theplurality of plugins based on a feature contained in the feature requestto a given network device or set of network devices, wherein theinstructions to cause the processor to map include instructions to causethe process to map between the requests for services and the plugins ina services abstraction layer so as to provide network level abstractionenabling the plurality of applications to interface via the differentSDN protocols with the network devices to implement a heterogeneousnetwork in which the network devices support the different SDN protocolsin an opaque fashion in order to fulfill the requests for services usingthe different SDN protocols; and send to respective ones of theplurality of network devices control messages from the selected pluginsaccording to appropriate ones of the plurality of different SDNprotocols.
 15. The computer readable storage media of claim 14, furthercomprising instructions that, when executed, cause the processor tostore, for each SDN protocol, one or more libraries of primitives usedfor communicating with a network device in accordance with acorresponding SDN protocol.
 16. The computer readable storage media ofclaim 15, wherein the libraries of primitives provide an abstraction soas to hide details of the plurality of different SDN protocols from theplurality of applications.
 17. The computer readable storage media ofclaim 15, wherein the instructions that, when executed, cause theprocessor to map comprise instructions that cause the processor toselect primitives of respective ones of the plurality of SDN protocolsto communicate a request for services of an application to a networkdevice.
 18. The computer readable storage media of claim 14, furthercomprising instructions that cause the processor to change or addplugins in order to accommodate changes or additions to the SDNprotocols.
 19. The computer readable storage media of claim 14, furthercomprising instructions that cause the processor to construct servicesusing individual features exposed by a plugin manager on behalf of theplurality of plugins.